graphql-mongoose-subscriptions/dist/messenger.js

A graphql-subscriptions PubSub Engine using mongoose

/* eslint-disable @typescript-eslint/no-empty-function */
/* eslint-disable @typescript-eslint/no-this-alias */
/* eslint-disable @typescript-eslint/no-var-requires */
/* eslint-disable no-undef */
'use strict';

var util = require('util');
var EventEmitter = require('events').EventEmitter;

function Messenger(options) {
  EventEmitter.apply(this, arguments);
  var o = options || {};
  if (o.mongooseOptions) {
    this.mongooseOptions = o.mongooseOptions;
  }
  var mongoose = o.mongoose || require('mongoose');
  this.mongoose = mongoose;

  var MessageSchema = new this.mongoose.Schema({
    channel: String,
    createdAt: { type: Date, expires: '15s', default: Date.now },
    message: mongoose.Schema.Types.Mixed
  });
  this.Message = mongoose.models['PubSubMessage'] || mongoose.model('PubSubMessage', MessageSchema);
  this.subscribed = {};
  this.lastMessageId = null;
  this.lastMessageTimestamp = null;
  this.startingMessageTimestamp = new Date();
  this.retryInterval = o.retryInterval || 100;
}

util.inherits(Messenger, EventEmitter);

Messenger.prototype.send = async function (channel, msg, callback) {
  var cb = function noop() {};
  if (typeof callback === 'function') {
    cb = callback;
  }
  var message = new this.Message({
    channel: channel,
    message: msg
  });
  try {
    await message.save();
    cb(message);
  } catch (e) {
    cb(e);
  }
};

Messenger.prototype.connect = function (callback) {
  var self = this;
  if (this.mongoose.connection.readyState == 0 && self.mongooseOptions) {
    this.mongoose.connect(self.mongooseOptions.url, self.mongooseOptions.options);
  }

  var pipeline = [{
    $match: {
      $or: [{ operationType: 'insert' }]
    }
  }];
  var stream = this.Message.watch(pipeline, { fullDocument: 'updateLookup' });

  stream.on('change', function data(doc) {
    var fullDocument = doc.fullDocument;

    if (fullDocument && self.subscribed[fullDocument.channel] && self.lastMessageId != fullDocument._id) {
      self.lastMessageId = fullDocument._id;
      self.lastMessageTimestamp = fullDocument.createdAt;
      self.emit(fullDocument.channel, fullDocument.message);
    }
  });

  // reconnect on error
  stream.on('error', function streamError() {
    if (stream && stream.destroy) stream.destroy();
    stream = null;
    setTimeout(function () {
      self.connect();
    }, 10000);
  });

  stream.on('close', function streamError() {
    if (stream && stream.destroy) stream.destroy();
    stream = null;
    setTimeout(function () {
      self.connect();
    }, 10000);
  });

  if (callback) callback();
};

Messenger.prototype.subscribe = function (channel, bool) {
  var self = this;
  if (channel && bool) {
    self.subscribed[channel] = bool;
    return;
  }
  if (channel && self.subscribed[channel]) {
    delete self.subscribed[channel];
  }
};

module.exports = Messenger;